Conventional refining of high-purity silicon is highly energy-intensive. For example, producing silicon of sufficiently high-purity for use in solar cells, semiconductor devices, and computer chips requires a very high amount of electrical energy. Such high energy demand creates significant costs, and in many instances, makes it prohibitively expensive to refine sufficiently high-purity silicon.
For example, the Siemens method of producing high-purity silicon comprises reducing trichlorosilane to polycrystalline silicon, which occurs by decomposing trichlorosilane on high-purity silicon rods or plates. This process is accomplished at greater than 1000° C., and utilizes water cooling to reduce the temperature of the reactor wall. As such, it requires a very high amount of electrical energy, and consequently, significantly high energy costs.
Because of the high energy usage and cost associated with producing sufficiently high-quality silicon, there exists a need for systems and methods which use less electrical energy. Accordingly, systems and methods to refine silicon in a more energy efficient way, for example by improving the purity of salts that are utilized in producing high-quality silicon and thereby reducing the amount of electrical energy required to refine silicon, are desired.